When producing microswitches for use in vehicles there is, for example, a requirement to adhesively bond the housing to the base and simultaneously to seal the connecting pins. The housings and the electrical connections leading out of the housings are sealed with a sealing compound. The housings may include, for example, caps and headers, and the electrical connections may include, for example, connecting pins.
In this method, a meniscus is formed at the interfaces of the individual components due to capillary action. When the sealing compound is metered and added to the exterior of the housing, said meniscus is larger since the sealing compound itself initially has a minimum height on top of which the meniscus forms. If the sealing compound is applied in the direct vicinity of the interfaces on which the seal is required, the meniscus increases in height due to separation drops.
Meniscus formation causes problems during the tin-plating process since solder beads may form due to the menisci. The solder beads cannot be readily found when checking the relay since they can generally move freely and therefore cannot always be located. For this reason manufacturing methods must be found which are able to prevent the formation of solder balls. The fact that the close contact between the connecting pins and their counterparts is no longer readily provided due to meniscus formation is also a disadvantage.
Until now, attempts to solve the problems of meniscus formation have involved conveying the sealing compound to the interface (for example a pin through the header) by means of conveying channels or ribs. In this case, capillary action is used to guide the sealing compound along the conveying channels or ribs to the interface to be sealed in order to then seal said surface.
Another proposed solution provides that the entire base area is structured. This means that the sealant or sealing compound spreads over the base plate by capillary action and thus also reaches the connections. This proposed solution requires that the sealant has an extremely low level of viscosity and that there are only very small gaps between the connecting pin and the housing. This has the drawback that very low component tolerances are required.